In the course of bronchial challenge, bronchopulmonary response assessment requires pleural pressure measurement. This measurement, mostly obtained in guinea pigs by a pleural catheter, is difficult to perform in anaesthetized paralysed ventilated animals needing periodical large inflations. The aim of this study was to demonstrate that the pulmonary response to intravenous histamine can be correctly appreciated from the respiratory response. In twelve anaesthetized paralysed mechanically ventilated guinea pigs, pulmonary and respiratory compliances (CL and Crs), were measured together with pulmonary and respiratory conductances (GL and Grs), using the method proposed by Rossi et al. (J. Appl. Physiol. 58: 1849-1858, 1985). Pulmonary and total respiratory mechanics were compared in the basal state, and at the end of a 5 min histamine infusion (100 ng.kg-1.sec-1). Pulmonary and respiratory compliances under histamine (HCL and HCrs), as well as pulmonary and respiratory conductances under histamine (HGL and HGrs), were expressed as a percentage of the corresponding basal values. Highly significant correlations were found between HCL and HCrs on the one hand (r = 0.98, P less than 0.001), and HGL and HGrs on the other (r = 0.97, P less than 0.001). We conclude that, in guinea pigs, the response of the total respiratory system to histamine infusion provides a simple and accurate assessment of the pulmonary response.